Mercedes-Benz GLE 450 W167

The GLE 450 uses a 48V mild hybrid system (EQ Boost) with a small lithium-ion battery that powers the integrated starter-generator and electric auxiliary compressor. Early 2019-2021 models are particularly affected by premature 48V battery failures. Mercedes identified three contributing factors: a painted ground contact point reducing conductivity, defective battery units, and outdated control software. Symptoms include a '48V On-Board Electrical System Malfunction' warning and an inability to start the vehicle, sometimes after sitting parked for just a few days. Mercedes released updated battery part numbers and software through Technical Service Bulletins. In the US, class-action lawsuits have been filed over this issue. Replacement typically costs €800-2,500 depending on whether a dealer or independent specialist performs the work. The 12V conventional battery can also drain if the car sits unused for more than 10-14 days. Post-2022 cars generally have the updated components.

The M256 engine uses a belt-driven integrated starter-generator (ISG) mounted between the engine and transmission. When this unit fails, it can cause sudden loss of power, no-start conditions, or dashboard warnings. The ISG part itself costs approximately €1,000-1,500, but labor is expensive because the transmission must be removed to access it. Total repair costs at a Mercedes dealer can reach €5,000-6,000; independent specialists may charge €3,000-4,000. Failures have been reported as early as 50,000 km, though most occur after 80,000 km. The 2024 facelift introduced a second-generation ISG relocated to the transmission housing, which Mercedes engineers acknowledge is more reliable. Pre-2024 models use the first-generation unit. This is the most expensive single repair risk on the GLE 450.

Many GLE W167 models are equipped with AIRMATIC air suspension. The rubber air springs become brittle and develop cracks over time, allowing air to escape. Symptoms include the car sitting lower on one corner after being parked overnight, or the compressor running excessively. A single OEM air strut costs approximately €800-1,200 per corner, with aftermarket alternatives from suppliers like Arnott available for €400-800. The compressor can also fail from overwork at an additional €600-1,000. A recall (20V-329) addressed defective piston seals in front struts and rear shock absorbers on certain 2020 models. Cars with standard steel spring suspension are not affected. When buying, check whether the car has AIRMATIC (visible from the ride height controls) and test by parking overnight to verify the car maintains its height.

Owners of M256-equipped vehicles have reported higher-than-expected oil consumption, which is often the first sign of piston ring issues. A specific manufacturing defect has been documented where the piston pin was not fully secured during assembly, potentially damaging cylinder walls and allowing oil past the rings. If oil consumption exceeds 0.5 litres per 1,000 km, investigation is warranted. At the less severe end, the valve cover gasket is a known leak point. This gasket deteriorates with heat cycles and can cause oil to drip onto the exhaust manifold, producing a burning smell in the cabin. Gasket replacement costs approximately €500-800. If piston ring replacement is required, a complete engine teardown is necessary, with costs exceeding €3,000 at specialist shops. Monitor oil levels carefully between services.

Some GLE 450 owners report rough downshifting from the 9G-Tronic, especially during cold starts, stop-and-go traffic, or light braking. A specific behavior where the transmission fails to fully complete a 7th-to-6th downshift under certain conditions was the subject of recall 24V-118, affecting 2020-2023 models. This recall covered approximately 105,000 vehicles. The recall remedy is a free software update at any Mercedes dealer. Outside the recall scope, shifting issues are commonly caused by adaptation drift, ATF condition, or valve body calibration. A transmission adaptation reset can often resolve mild symptoms at minimal cost. If the valve body requires replacement, costs reach €1,500-2,500. Mercedes recommends transmission fluid changes every 60,000-80,000 km despite some references to it being a lifetime fill. Regular fluid changes are strongly recommended.

The MBUX infotainment system can occasionally fail to start properly, displaying a completely black centre screen. When this occurs, navigation, reversing cameras, and audio are unavailable. A recall (21V354) addressed 2019-2021 models where the system would not start or would reboot after 50 seconds. The remedy was a software update, available over-the-air for cars with a Mercedes Me subscription. In persistent cases, the head unit module (located under the passenger seat) needs replacement at €800-1,200. Other reported issues include Apple CarPlay disconnections, inconsistent heating between driver and passenger zones, and the audio system occasionally activating at full volume while parked. Most software-related issues can be resolved through dealer-applied updates at no cost.

As a direct-injection engine, the M256 is susceptible to carbon buildup on the intake valves because fuel is injected directly into the cylinders rather than washing over the valves. Over time, oil vapors from the crankcase ventilation system bake onto the valve surfaces, causing rough idle, misfires, and reduced power. This typically becomes noticeable after 80,000-120,000 km. The standard remedy is walnut shell blasting of the intake ports, which costs approximately €400-800 at an independent specialist or €800-1,200 at a Mercedes dealer. Some owners schedule this preventively every 80,000-100,000 km. Using quality fuel and allowing the engine to reach full operating temperature regularly can delay carbon buildup.